Asthma is the most common indication for hospitalization and is the most common chronic disease of childhood. In animal models, IL-13 plays a key role in the development of asthma and allergic inflammation. We have demonstrated in our preliminary data that IL-13R alpha 2 is an intracellular molecule and its activation-dependent surface expression inhibits IL-13 signaling. This proposal describes a 5-year mentored training program for the development of an academic career in basic science research. The proposal will investigate surface expression regulation, subcellular localization, the mechanism of IL-13 signal suppression, and the related key structural motifs of IL-13R alpha 2. We will examine the role of a broad panel of regulatory cytokines in modulating its surface expression. Subcellular localization will be studied by confocal microscopy examining colocalization with known subcellular compartments. Transfection models will allow study of the effect of overexpression of this receptor. We have generated an in vitro model of IL-13 signaling that lacks competing endogenous IL-13 receptors. We will study IL-13 dependent signaling in these cells. We will generate cells expressing increasing amounts of IL-13R alpha 2 and determine if there is a dose-response of increasing expression of this molecule. This model will also be used to determine what structural elements are important to IL-13R alpha 2 modulating IL-13 signaling. IL-13R alpha 2 mutants will be created, truncating the protein to delete the cytoplasmic region, mutating the cytoplasmic tyrosine, or mutating the tri-leucine region that has been demonstrated to affect receptor internalization. We will study protein stability, IL-13 binding affinity, surface expression, and the effect on modulating IL-13 signaling in these mutants compared to wild type IL-13R alpha 2. This novel transfection model will determine the key structural elements in the IL-13R alpha 2 that allow inhibition of IL-13 signaling. This application represents the first extensive study of IL-13R alpha 2 cytokine dependent surface expression, its role in modulating IL-13 signaling, and the structural elements of IL-13R alpha 2 that are involved.